ntdll: Ignore the preload start address if it is zero.

dlls/ntdll/virtual.c

@@ -1597,7 +1597,8 @@ void virtual_init(void)
             preload_reserve_start = (void *)start;
             preload_reserve_end = (void *)end;
             /* some apps start inside the DOS area */
-            address_space_start = min( address_space_start, preload_reserve_start );
+            if (preload_reserve_start)
+                address_space_start = min( address_space_start, preload_reserve_start );
         }
     }